What differentiates natural vibration from other types of vibration?

Natural vibration refers to the inherent modes of oscillation that a structure or mechanical system tends to exhibit when it is disturbed from its equilibrium position. Each structure has specific frequencies, known as natural frequencies, where it will vibrate freely in response to a disturbance. These frequencies are determined by the physical properties of the structure, such as its mass, stiffness, and boundary conditions.

When a structure is excited at one of these natural frequencies, it can resonate, leading to increased amplitude of vibration. This makes understanding natural vibration crucial in fields such as civil engineering and mechanical design, where improper handling of these vibrations can result in significant structural issues, including failure.

In contrast, other types of vibration may arise due to external factors, such as applied loads or operational activities, and are not exclusively tied to the physical characteristics of the structure itself. Thus, the defining aspect of natural vibration is that it corresponds to the frequencies a structure naturally prefers to oscillate at, without being influenced by external forces, at least in the context of its inherent vibration properties.